Boost Converter (Step-Up)
Calculate the output voltage of a boost (step-up) DC-DC converter in continuous conduction, V_out = V_in ÷ (1 − D), from the input voltage V_in and the duty cycle D (0 to 1). The result, in volts, is always greater than the input — the boost converter raises voltage by storing energy in an inductor and releasing it in series with the source. As D approaches 1, the output tends to infinity (limited by real losses). It is used in supplies that must step up voltage (LEDs, batteries, power factor correction) and in photovoltaic systems. Enter the input voltage and the duty cycle.
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Boost converter (step-up)
The boost converter does the opposite of the buck: it steps up a DC voltage. In continuous conduction its relation is V_out = V_in ÷ (1 − D), where D is the duty cycle. Since (1 − D) < 1, the output is always higher than the input — and it climbs quickly as D approaches 1 (at D = 0.5 the output doubles; at D = 0.8 it is five times the input). The working principle is ingenious: during the 'on' part of the cycle the switch ties the inductor to the source and the inductor stores energy in its magnetic field (the current ramps up); during the 'off' part the inductor sits in series with the input source, and its voltage adds to the source voltage, pushing energy through a diode into a capacitor that holds up the raised output. In theory D → 1 would give infinite output, but in practice the real losses (winding and switch resistance, diode drop) cap the gain at around 5-10× and efficiency falls off at high gains. The boost is essential whenever a voltage higher than the available source is required: driving LEDs in series from a low-voltage battery, power factor correction (PFC) at the front end of power supplies, raising the voltage of photovoltaic panels or of a single battery cell, and in audio amplifiers and camera flash circuits. Enter the input voltage and the duty cycle.
Related Tools
Buck Converter (Step-Down)
Calculate the output voltage of a buck (step-down) DC-DC converter in continuous conduction, V_out = D × V_in, from the duty cycle D (0 to 1) and the input voltage V_in. The result, in volts, is always less than or equal to the input — the buck converter lowers voltage efficiently (without dissipating the excess, unlike a linear regulator), by switching rapidly and filtering with an inductor and capacitor. Varying the duty cycle adjusts the output from 0 to V_in. It is the most common topology in switching power supplies and point-of-load regulators. Enter the duty cycle and the input voltage.
Buck-Boost Converter
Calculate the output voltage of a buck-boost DC-DC converter in continuous conduction, V_out = V_in × D ÷ (1 − D), from the input voltage V_in and the duty cycle D (0 to 1). The result, in volts, can be lower (D < 0.5) or higher (D > 0.5) than the input — the buck-boost converter steps voltage down or up depending on the duty cycle, with inverted output polarity in the classic topology. It is used when the input voltage can vary above and below the desired output (discharging batteries, universal supplies). Enter the input voltage and the duty cycle.
Square-Wave RMS Current
Calculate the RMS value of a pulsing square-wave current, I_rms = I_p × √D, from the peak current I_p and the duty cycle D (fraction of the period the current flows). The result, in amperes, is the RMS current that determines the actual heating (I²R losses) of a component that conducts in pulses — such as a transistor or winding in a switching converter. Unlike the average value, the RMS is what matters for sizing conductors, resistances and dissipation. The smaller the duty cycle, the lower the RMS for the same peak current. Enter the peak current and the duty cycle.
PWM Output Voltage
Calculate the average output voltage of a PWM signal, V_out = (duty ÷ 100) × V_sup, from the duty cycle (in %) and the supply voltage V_sup. The result, in volts, is the effective average voltage delivered to a load (motor, LED, heater) by rapidly switching the supply on and off. Varying the duty cycle from 0 to 100% varies the average voltage from 0 to V_sup, allowing power control without dissipating energy in resistors — the basis of motor speed and LED brightness control in microcontrollers. Enter the duty cycle and the supply voltage.
Output Voltage Ripple
Calculate the output voltage ripple of a switching converter, ΔV = I ÷ (f × C), from the output current I, the switching frequency f and the output capacitance C. The result, in volts, is the residual oscillation superimposed on the DC output voltage, caused by the filter capacitor charging and discharging each switching cycle. Higher frequency and capacitance reduce the ripple. Keeping the ripple within limits (typically <1% of the output) is essential to supply sensitive circuits. Enter the current, the switching frequency and the capacitance.
Junction Temperature
Calculate the junction temperature of a power semiconductor, T_j = T_a + P × R_th, from the ambient temperature T_a, the dissipated power P and the total junction-to-ambient thermal resistance R_th (°C/W). The result, in °C, is the device's internal temperature (silicon junction), which must not exceed the manufacturer's limit (typically 150 °C) on pain of failure. The thermal resistance adds the junction-to-case, case-to-heatsink and heatsink-to-ambient stages. Lowering R_th (larger heatsink, ventilation, thermal paste) lowers the junction temperature. It is the central calculation of power electronics thermal design. Enter the ambient temperature, the dissipated power and the thermal resistance.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.